This invention relates to automatically designing custom power converters.
Power converters accept power from an electrical input source and convert it into a form suitable for use by electrical loads. One class of power conversion systems, called power supplies, are typically used to convert power derived from a utility source, such as an AC utility line or a DC telecommunications battery, into one or more regulated DC voltages (e.g., 5V, 12V, 48V) used for powering electronic circuitry. Specifications for a power supply are application specific. Thus, while many power supplies may share certain common characteristics such as a similar input voltage range or the presence of a 5-volt output, many power supplies are customized, by design, for use in a particular product or system.
Design of a custom power supply involves different skills and usually takes months to complete. For example, a typical custom power supply design may involve design of electronic power conversion circuitry; design, layout and procurement of printed circuit boards, packaging and cooling elements, source interface “front-end” circuitry (such as power factor correcting front-end circuitry or “auto-ranging” rectification circuitry for use with AC utility sources) and conducted EMI filter components; fabrication of prototype assemblies; qualification and testing of prototypes with respect to electrical, thermal, mechanical and EMI/RFI specifications; and acquisition and submission of test data for obtaining safety agency (e.g., Underwriters Laboratories, Canadian Standards Association) approvals. In addition, money and effort must also usually be invested in the development and qualification of manufacturing processes and equipment for each different custom power supply.
Widespread commercial availability of high density power components such as modular DC-DC power converters and related front-end power components helped simplify and shorten the custom power supply design cycle by eliminating the need to design, qualify and obtain agency approvals on power conversion and front-end interface circuitry. However, weeks or months of effort are still often required to perform the packaging, thermal and other design and qualification tasks required to develop a custom power supply using power components.
General Electric Corporation has offered prepackaged modular building blocks for configuring switching power conversion circuits. Each building block (e.g., rectifier block, switch block, output filter block) formed a portion of a switching power converter circuit and each was available in various voltage and current ratings to allow configuring supplies of different input voltage, output voltage, and power ratings. A microcomputer-based software package aided the user in selecting those building blocks which, when connected together, would result in a power converter which meets the user's functional requirements. The software selected those pre-defined blocks which would result in a certain combination of input voltage, output voltage, and power level.
Linear Technology Corporation, Milpitas, Calif., USA, has offered a software based power supply design program called SwitcherCAD; and National Semiconductor Corporation, Santa Clara, Calif., USA, has offered a software based power supply design program called Simple Switcher. Both programs accept a set of predefined functional specifications and generate parts lists and schematics for a power conversion circuit which meets the specifications. Both programs can produce designs for different topologies (e.g., isolated flyback, non-isolated PWM buck). The user of the programs can modify component values and other design parameters and observe the effects on performance, e.g., conversion efficiency. Both programs use pre-defined equations for generating a solution.
Siemens has announced an expert system which runs on a personal computer for aiding in the design of power supplies. It collects specifications for the power supply from the user, synthesizes possible structures, and reports the number of feasible solutions for the selected input/output description. The price for a specified quantity and lot size are calculated by the system. The configuration report is sent to the manufacturer's computer over a wide area network and then passed on to the development department.
The manufacturer then designs the power supply. Circuit macros stored in a CAD system are called up, placed, and the clusters are connected together to reduce development costs. The development time for designing the power supply is typically four working days which is apparently performed by the design engineers at the manufacturer.